Comparison               package:base               R Documentation

_R_e_l_a_t_i_o_n_a_l _O_p_e_r_a_t_o_r_s

_D_e_s_c_r_i_p_t_i_o_n:

     Binary operators which allow the comparison of values in vectors.

_U_s_a_g_e:

     x < y
     x > y
     x <= y
     x >= y
     x == y
     x != y

_D_e_t_a_i_l_s:

     Comparison of strings in character vectors is lexicographic within
     the strings using the collating sequence of the locale in use: see
     'locales'.  The collating sequence of locales such as 'en_US' is
     normally different from 'C' (which should use ASCII) and can be
     surprising.

_V_a_l_u_e:

     A vector of logicals indicating the result of the element by
     element comparison.  The elements of shorter vectors are recycled
     as necessary.

     Objects such as arrays or time-series can be compared this way
     provided they are conformable.

_N_o_t_e:

     Don't use '==' and '!=' for tests, such as in 'if' expressions,
     where you must get a single 'TRUE' or 'FALSE'.  Unless you are
     absolutely sure that nothing unusual can happen, you should use
     the 'identical' function instead.

     For numerical values, remember '==' and '!=' do not allow for the
     finite representation of fractions, nor for rounding error. Using
     'all.equal' with 'identical' is almost always preferable.  See the
     examples.

_R_e_f_e_r_e_n_c_e_s:

     Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) _The New S
     Language_. Wadsworth & Brooks/Cole.

_S_e_e _A_l_s_o:

     'Syntax' for operator precedence.

_E_x_a_m_p_l_e_s:

     x <- rnorm(20)
     x < 1
     x[x > 0]

     x1 <- 0.5 - 0.3
     x2 <- 0.3 - 0.1
     x1 == x2                           # FALSE on most machines
     identical(all.equal(x1, x2), TRUE) # TRUE everywhere

